Method for the selective production of racemic metallocene complexes

ABSTRACT

The invention relates to a method for producing racemic metallocene complexes by reacting bridged or non-bridged transition metal complexes with cyclopentadienyl derivatives of alkaline or alkaline earth metals and optionally, subsequently substituting the phenolate ligands.

[0001] The present invention relates to a process for preparing racemicmetallocene complexes by reacting bridged or unbridged transitionmetal-aromatic complexes of the formula I

[0002] where the substituents and indices have the following meanings:

[0003] M is titanium, zirconium, hafnium, vanadium, niobium, tantalum,chromium, molybdenum, tungsten or an element of transition group III ofthe Periodic Table or a lanthanide,

[0004] X are identical or different and are each fluorine, chlorine,bromine, iodine, hydrogen, C₁-C₁₀-alkyl, C₆-C₁₅-aryl, alkylaryl havingfrom 1 to 10 carbon atoms in the alkyl part and from 6 to 20 carbonatoms in the aryl part, —OR¹⁰ or —NR¹⁰R¹¹,

[0005] n is an integer from 1 to 4, where n corresponds to the valenceof M minus 2,

[0006] R¹, R⁸ are identical or different and are each hydrogen,fluorine, chlorine, bromine, iodine, C₁-C₂₀-alkyl, 3- to 8-memberedcycloalkyl which may in turn bear a C₁-C₁₀-alkyl group as substituent,C₆-C₁₅-aryl, alkylaryl having from 1 to 10 carbon atoms in the alkylpart and from 6 to 20 carbon atoms in the aryl part, arylalkyl havingfrom 1 to 10 carbon atoms in the alkyl part and from 6 to 20 carbonatoms in the aryl part, Si(R⁹)₃ where R⁹ are identical or different andare each C₁-C₂₀-alkyl, C₃-C₁₀-cycloalkyl, C₆-C₁₅-aryl, where theradicals mentioned may be partially or fully substituted by heteroatoms,—OR²⁷, —SR²⁷, —N(R²⁷)₂, —P(R²⁷)₂, where R²⁷ are identical or differentand are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl orSi(R²⁸)₃ where R²⁸ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl

[0007] R² to R⁷ are identical or different and are each hydrogen,C₁-C₂₀-alkyl, 3- to 8-membered cycloalkyl which may in turn bear aC₁-C₁₀-alkyl radical as substituent, C₆-C₁₅-aryl, alkylaryl having from1 to 10 carbon atoms in the alkyl part and from 6 to 20 carbon atoms inthe aryl part, arylalkyl having from 1 to 10 carbon atoms in the alkylpart and from 6 to 20 carbon atoms in the aryl part, Si(R⁹)₃ where R⁹are identical or different and are each C₁-C₂₀-alkyl, C₃-C₁₀-cycloalkyl,C₆-C₁₅-aryl, where adjacent radicals R² to R⁷ may form saturated,partially saturated or unsaturated cyclic groups having from 4 to 15carbon atoms, and the radicals mentioned may be fully or partiallysubstituted by heteroatoms, —OR²⁷, —SR²⁷, —N(R²⁷)₂, —P(R²⁷)₂, where R²⁷are identical or different and are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl,C₃-C₁₀-cycloalkyl, alkylaryl or Si(R²⁸)₃ where R²⁸ are identical ordifferent and are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl,alkylaryl

[0008] R¹⁰, R¹¹ are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl, alkylaryl,arylalkyl, fluoroalkyl or fluoroaryl each having from 1 to 10 carbonatoms in the alkyl radical and from 6 to 20 carbon atoms in the arylradical,

[0009] Y, Y¹ are identical or different and are each

[0010]  ═BR¹², ═AlR¹², —Ge—, —Sn—, —O—, —S—, ═SO, ═SO₂, ═NR¹², ═CO,═PR¹² or ═P(O)R¹²,

[0011] where

[0012] R¹² are identical or different and are each hydrogen, halogen,C₁-C₁₀-alkyl, C₁-C₁₀-fluoroalkyl, C₆-C₁₀-fluoroaryl, C₆-C₁₀-aryl,C₁-C₁₀-alkoxy, C₂-C₁₀-alkenyl, C₇-C₄₀-arylalkyl, C₈-C₄₀-arylalkenyl,C₇-C₄₀-alkylaryl, or two radicals R¹² together with the atoms connectingthem form a ring,

[0013] M¹ is silicon, germanium or tin and

[0014] m is 0, 1, 2, 3,

[0015] or Y is nonbridging and represents two radicals R′ and R″, where

[0016] R′ and R″ are identical or different and are each hydrogen,fluorine, chlorine, bromine, iodine, C₁-C₂₀-alkyl, 3- to 8-memberedcycloalkyl which may in turn bear a C₁-C₁₀-alkyl group as substituent,C₆-C₁₅-aryl, alkylaryl having from 1 to 10 carbon atoms in the alkylpart and from 6 to 20 carbon atoms in the aryl part, arylalkyl havingfrom 1 to 10 carbon atoms in the alkyl part and from 6 to 20 carbonatoms in the aryl part, Si(R⁹)₃ where R⁹ are identical or different andare each C₁-C₂₀-alkyl, C₃-C₁₀-cycloalkyl, C₆-C₁₅-aryl or together withadjacent radicals R⁴ or R⁵ form saturated, partially saturated orunsaturated cyclic groups having from 4 to 15 carbon atoms, and theradicals mentioned may be fully or partially substituted by heteroatoms,—OR²⁷, —SR²⁷, —N(R²⁷)₂, —P(R²⁷)₂, where R²⁷ are identical or differentand are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl orSi(R²⁸)₃ where R²⁸ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl

[0017] with cyclopentadienyl derivatives of alkali metals or alkalineearth metals, heating the reaction mixture obtained in this way to from−78 to 250° C., with or without addition of free radicals or freeradical formers, and, if desired, subsequently replacing the bridgedphenolic ligand or the two unbridged phenolic ligands to form themonosubstitution or disubstitution product; racemic metallocenecomplexes of the formula III

[0018] where the substituents and indices have the following meanings:

[0019] M is titanium, zirconium, hafnium, vanadium, niobium, tantalum,chromium, molybdenum, tungsten or an element of transition group III ofthe Periodic Table or a lanthanide,

[0020] X¹ is

[0021] where:

[0022] R¹, R⁸ are identical or different and are each hydrogen,fluorine, chlorine, bromine, iodine, C₁-C₂₀-alkyl, 3- to 8-memberedcycloalkyl which may in turn bear a C₁-C₁₀-alkyl group as substituent,C₆-C₁₅-aryl, alkylaryl having from 1 to 10 carbon atoms in the alkylpart and from 6 to 20 carbon atoms in the aryl part, arylalkyl havingfrom 1 to 10 carbon atoms in the alkyl part and from 6 to 20 carbonatoms in the aryl part, Si(R⁹)₃ where R⁹ are identical or different andare each C₁-C₂₀-alkyl, C₃-C₁₀-cycloalkyl, C₆-C₁₅-aryl, where theradicals mentioned may be partially or fully substituted by heteroatoms,—OR²⁷, —SR²⁷, —N(R²⁷)₂, —P(R²⁷)₂, where R²⁷ are identical or differentand are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl orSi(R²⁸)₃ where R²⁸ are identical or different and are eachC_(l)-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl

[0023] R² to R⁷ are identical or different and are each hydrogen,C₁-C₂₀-alkyl, 3-to 8-membered cycloalkyl which may in turn bear aC₁-C₁₀-alkyl radical as substituent, C₆-C₁₅-aryl, alkylaryl having from1 to 10 carbon atoms in the alkyl part and from 6 to 20 carbon atoms inthe aryl part, arylalkyl having from 1 to 10 carbon atoms in the alkylpart and from 6 to 20 carbon atoms in the aryl part, Si(R⁹)₃ where R⁹are identical or different and are each C₁-C₂₀-alkyl, C₃-C₁₀-cycloalkyl,C₆-C₁₅-aryl, where adjacent radicals R² to R⁷ may form saturated,partially saturated or unsaturated cyclic groups having from 4 to 15carbon atoms, and the radicals mentioned may be fully or partiallysubstituted by heteroatoms, —OR²⁷, —SR²⁷, —N(R²⁷)₂, —P(R²⁷)₂, where R²⁷are identical or different and are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl,C₃-C₁₀-cycloalkyl, alkylaryl or Si(R²⁸)₃ where R²⁸ are identical ordifferent and are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl,alkylaryl

[0024] Y, Y¹ are identical or different and are each

[0025]  ═BR¹², ═AlR¹², —Ge—, —Sn—, —O—, —S—, ═SO, ═SO₂, ═NR¹², ═CO,═PR¹² or ═P(O)R¹²,

[0026] where

[0027] R¹² are identical or different and are each hydrogen, halogen,C₁-C₁₀-alkyl, C₁-C₁₀-fluoroalkyl, C₆-C₁₀-fluoroaryl, C₆-C₁₀-aryl,C₁-C₁₀-alkoxy, C₂-C₁₀-alkenyl, C₇-C₄₀-arylalkyl, C₈-C₄₀-arylalkenyl,C₇-C₄₀-alkylaryl, or two radicals R¹² together with the atoms connectingthem form a ring,

[0028] M¹ is silicon, germanium or tin and

[0029] m is 0, 1, 2, 3,

[0030] or Y is nonbridging and represents two radicals R′ and R″, where

[0031] R′ and R″ are identical or different and are each hydrogen,fluorine, chlorine, bromine, iodine, C₁-C₂₀-alkyl, 3- to 8-memberedcycloalkyl which may in turn bear a C₁-C₁₀-alkyl group as substituent,C₆-C₁₅-aryl, alkylaryl having from 1 to 10 carbon atoms in the alkylpart and from 6 to 20 carbon atoms in the aryl part, arylalkyl havingfrom 1 to 10 carbon atoms in the alkyl part and from 6 to 20 carbonatoms in the aryl part, Si(R⁹)₃ where R⁹ are identical or different andare each C₁-C₂₀-alkyl, C₃-C₁₀-cycloalkyl, C₆-C₁₅-aryl or together withadjacent radicals R⁴ or R⁵ form saturated, partially saturated orunsaturated cyclic groups having from 4 to 15 carbon atoms, and theradicals mentioned may be fully or partially substituted by heteroatoms,—OR²⁷, —SR²⁷, —N(R²⁷)₂, —P(R²⁷)₂, where R²⁷ are identical or differentand are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl orSi(R²⁸)₃ where R²⁸ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl,

[0032] R¹³ to R¹⁷ are identical or different and are each hydrogen,C₁-C₂₀-alkyl, 5- to 7-membered cycloalkyl which may in turn bear aC₁-C₁₀-alkyl group as substituent, C₆-C₁₅-aryl or arylalkyl, whereadjacent radicals may together form cyclic groups having from 4 to 15carbon atoms, or Si(R¹⁸)₃ where

[0033] R¹⁸ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl or C₃-C₁₀-cycloalkyl,

[0034] Z is

[0035]  where the radicals

[0036] R¹⁹ to R²³ are identical or different and are each hydrogen,C₁-C₂₀-alkyl, 5- to 7-membered cycloalkyl which may in turn bear aC₁-C₁₀-alkyl group as substituent, C₆-C₁₅-aryl or arylalkyl, whereadjacent radicals may together form cyclic groups having from 4 to 15carbon atoms, or Si(R²⁴)₃ where

[0037] R²⁴ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl or C₃-C₁₀-cycloalkyl,

[0038] or

[0039] R¹⁶ and Z together form a —[T(R²⁵)(R²⁶)]_(q)—E— group in which

[0040] T may be identical or different and are each silicon, germanium,tin or carbon,

[0041] R²⁵, R²⁶ are each hydrogen, C₁-C₁₀-alkyl, C₃-C₁₀-cycloalkyl orC₆-C₁₅-aryl

[0042] q is 1, 2, 3 or 4,

[0043] E is

[0044] where R²⁷ is C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl,alkylaryl or Si(R²⁸)₃

[0045] where R²⁸ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl or alkylaryl,

[0046] and the use of racemic metallocene complexes of the formula IIIas catalysts or as constituents of catalysts for the polymerization ofolefinically unsaturated compounds or as reagents or catalysts instereoselective synthesis.

[0047] In addition to the stereoselective polymerization of olefins, theenantioselective synthesis of organic compounds increasingly offersinteresting possible applications of chiral metallocene complexes ofmetals of transition groups III-VI of the Periodic Table of theElements. Examples which may be mentioned are enantioselectivehydrogenations of prochiral substrates, for example prochiral olefins,as described in R. Waymouth, P. Pino, J. Am. Chem. Soc. 112 (1990), pp.4911-4914, or prochiral ketones, imines and oximes as described in WO92/9545.

[0048] Further examples are the preparation of optically active alkenesby enantioselective oligomerization as described in W. Kaminsky et al.,Angew. Chem. 101 (1989), pp. 1304-1306, and the enantioselectivecyclopolymerization of 1,5-hexadienes as described in R. Waymouth, G.Coates, J. Am. Chem. Soc. 113 (1991), pp. 6270 - 6271.

[0049] The applications mentioned generally require the use of ametallocene complex in its racemic form, i.e. without meso compounds. Inthe case of the mixture of diastereomers (rac. and meso forms) obtainedin the metallocene synthesis of the prior art, the meso form firstly hasto be separated off. Since the meso form has to be discarded, the yieldof racemic metallocene complex is low.

[0050] It is an object of the present invention to find a process forselectively preparing racemic metallocene complexes which are virtuallyfree (to within NMR measurement accuracy) of meso isomer. A furtherobject is to find racemic metallocene complexes which can either be useddirectly as catalysts or in catalysts, primarily for the polymerizationof olefins, or can be used as catalysts or in catalysts, primarily forthe polymerization of olefins, after modification, for example afterreplacement of an “auxilary ligand”, or can be used as reagents orcatalysts in stereoselective synthesis.

[0051] We have found that these objects are achieved by the processdefined in the claims, by the racemic metallocene complexes III and bytheir use as catalysts or in catalysts for the polymerization ofolefinically unsaturated compounds or as reagents or catalysts instereoselective synthesis.

[0052] The terms “meso form”, “racemate” and thus also “enantiomers” inthe context of metallocene complexes are known and defined, for example,in Rheingold et al., Organometallics 11 (1992), pp. 1869-1876.

[0053] For the purposes of the present invention, the expression“virtually meso free” means that at least 90% of a compound are presentin the form of the racemate.

[0054] The bridged or unbridged transition metal-aromatic complexes usedaccording to the present ivnention have the formula I

[0055] where the substituents and indices have the following meanings:

[0056] M is titanium, zirconium, hafnium, vanadium, niobium, tantalum,chromium, molybdenum, tungsten or an element of transition group III ofthe Periodic Table or a lanthanide,

[0057] X are identical or different and are each fluorine, chlorine,bromine, iodine, hydrogen, C₁-C₁₀-alkyl, C₆-C₁₅-aryl, alkylaryl havingfrom 1 to 10 carbon atoms in the alkyl part and from 6 to 20 carbonatoms in the aryl part, —OR¹⁰ or —NR¹⁰R¹¹,

[0058] n is an integer from 1 to 4, where n corresponds to the valenceof M minus 2,

[0059] R¹, R⁸ are identical or different and are each hydrogen,fluorine, chlorine, bromine, iodine, C₁-C₂₀-alkyl, 3- to 8-memberedcycloalkyl which may in turn bear a C₁-C₁₀-alkyl group as substituent,C₆-C₁₅-aryl, alkylaryl having from 1 to 10 carbon atoms in the alkylpart and from 6 to 20 carbon atoms in the aryl part, arylalkyl havingfrom 1 to 10 carbon atoms in the alkyl part and from 6 to 20 carbonatoms in the aryl part, Si(R⁹)₃ where R⁹ are identical or different andare each C₁-C₂₀-alkyl, C₃-C₁₀-cycloalkyl, C₆-C₁₅-aryl, where theradicals mentioned may be partially or fully substituted by heteroatoms,—OR²⁷, —SR²⁷, —N(R²⁷)₂, —P(R²⁷)₂, where R²⁷ are identical or differentand are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl orSi(R²⁸)₃ where R²⁸ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl

[0060] R² to R⁷ are identical or different and are each hydrogen,C₁-C₂₀-alkyl, 3-to 8-membered cycloalkyl which may in turn bear aC₁-C₁₀-alkyl radical as substituent, C₆-C₁₅-aryl, alkylaryl having from1 to 10 carbon atoms in the alkyl part and from 6 to 20 carbon atoms inthe aryl part, arylalkyl having from 1 to 10 carbon atoms in the alkylpart and from 6 to 20 carbon atoms in the aryl part, Si(R⁹)₃ where R⁹are identical or different and are each C_(l)-C₂₀-alkyl,C₃-C₁₀-cycloalkyl, C₆-C₁₅-aryl, where adjacent radicals R² to R⁷ mayform saturated, partially saturated or unsaturated cyclic groups havingfrom 4 to 15 carbon atoms, and the radicals mentioned may be fully orpartially substituted by heteroatoms, —OR²⁷, —SR²⁷, —N(R²⁷)₂, —P(R²⁷)₂,where R²⁷ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl or Si(R²⁸)₃ where R²⁸ areidentical or different and are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl,C₃-C₁₀-cycloalkyl, alkylaryl

[0061] R¹⁰, R¹¹ are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl, alkylaryl,arylalkyl, fluoroalkyl or fluoroaryl each having from 1 to 10 carbonatoms in the alkyl radical and from 6 to 20 carbon atoms in the arylradical,

[0062] Y, Y¹ are identical or different and are each

[0063]  ═BR¹², ═AlR¹², —Ge—, —Sn—, —O—, —S—, ═SO, ═SO₂, ═NR¹², ═CO,═PR¹² or ═P(O)R¹²,

[0064] where

[0065] R¹² are identical or different and are each hydrogen, halogen,C₁-C₁₀-alkyl, C₁-C₁₀-fluoroalkyl, C₆-C₁₀-fluoroaryl, C₆-C₁₀-aryl,C₁-C₁₀-alkoxy, C₂-C₁₀-alkenyl, C₇-C₄₀-arylalkyl, C₈-C₄₀-arylalkenyl,C₇-C₄₀-alkylaryl, or two radicals R¹² together with the atoms connectingthem form a ring,

[0066] M¹ is silicon, germanium or tin and

[0067] m is 0, 1, 2, 3,

[0068] or Y is nonbridging and represents two radicals R′ and R″, where

[0069] R′ and R″ are identical or different and are each hydrogen,fluorine, chlorine, bromine, iodine, C₁-C₂₀-alkyl, 3- to 8-memberedcycloalkyl which may in turn bear a C₁-C₁₀-alkyl group as substituent,C₆-C₁₅-aryl, alkylaryl having from 1 to 10 carbon atoms in the alkylpart and from 6 to 20 carbon atoms in the aryl part, arylalkyl havingfrom 1 to 10 carbon atoms in the alkyl part and from 6 to 20 carbonatoms in the aryl part, Si(R⁹)₃ where R⁹ are identical or different andare each C₁-C₂₀-alkyl, C₃-C₁₀-cycloalkyl, C₆-C₁₅-aryl or together withadjacent radicals R⁴ or R⁵ form saturated, partially saturated orunsaturated cyclic groups having from 4 to 15 carbon atoms, and theradicals mentioned may be fully or partially substituted by heteroatoms.

[0070]  —OR²⁷, —SR²⁷, —N(R²⁷)₂, —P(R²⁷)₂, where R²⁷ are identical ordifferent and are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl,alkylaryl or Si(R²⁸)₃ where R²⁸ are identical or different and are eachC₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl.

[0071] Preferred metals M are titanium, zirconium and hafnium, inparticular zirconium.

[0072] Well-suited substituents X are fluorine, chlorine, bromine,iodine, preferably chlorine, also C₁-C₆-alkyl such as methyl, ethyl,n-propyl, isopropyl, n-butyl, sec-butyl, i-butyl, preferably tert-butyl.Further useful substituents X are alkoxides —OR¹⁰ or amides —NR¹⁰R¹¹where R¹⁰ or R¹¹ is C₁-C₁₀-alkyl, C₆-C₁₅-aryl, alkylaryl, arylalkyl,fluoroalkyl or fluoroaryl each having from 1 to 10 carbon atoms in thealkyl radical and from 6 to 20 carbon atoms in the aryl radical. Suchradicals X are, for example, methyl, ethyl, i-propyl, tert-butyl,phenyl, naphthyl, p-tolyl, benzyl, trifluoromethyl, pentafluorophenyl.

[0073] The substituents R¹ and R⁸ are identical or different and areeach hydrogen, fluorine, chlorine, bromine, iodine, C₁-C₂₀-alkyl, —OR²⁷,—SR²⁷, —N(R²⁷)₂, —P(R²⁷)₂, where R²⁷ are identical or different and areeach C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl or Si(R²⁸)₃where R²⁸ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl, 3- to 8-membered cycloalkylwhich may in turn bear a C₁-C₁₀-alkyl radical such as methyl, ethyl orpropyl as substituent. Examples of such cycloalkyl radicals arecyclopropyl, cyclopentyl, preferably cyclohexyl, norbornyl. Thesubstituents R¹ and R⁸ may also be C₆-C₁₅-aryl such as phenyl, naphthyl;alkylaryl having from 1 to 10 carbon atoms in the alkyl part and from 6to 20 carbon atoms in the aryl part, e.g. p-tolyl; arylalkyl having from1 to 10 carbon atoms in the alkyl part and from 6 to 20 carbon atoms inthe aryl part, e.g. benzyl, neophyl, or they may be triorganosilyl suchas Si(R⁹)₃ where R⁹ are identical or different and are eachC₁-C₂₀-alkyl, C₃-C₁₀-cycloalkyl, C₆-C₁₅-aryl, for exampletrimethylsilyl, tert-butyldimethylsilyl, triphenylsilyl. The radicalsmentioned can, of course, also be partially or fully substituted byheteroatoms, for example by S-, N-, O- or halogen-containing structuralelements. Examples of such substituted radicals R¹ and R⁸ are thetrifluoromethyl, pentafluoroethyl, heptafluoropropyl,heptafluoroisopropyl and pentafluorophenyl groups.

[0074] Preferred substituents R¹ and R⁸ are those which take up a largeamount of space. Such substituents are usually referred to as bulkysubstituents and they can cause steric hindrance.

[0075] For the purposes of the present invention, these groups aregenerally organic or organosilicon radicals which take up a large amountof space (bulky radicals), but also fluorine and preferably chlorine,bromine and iodine. The number of carbon atoms in such organic ororganosilicon radicals is usually not less than three.

[0076] Preferred nonaromatic, bulky radicals are organic ororganosilicon radicals which are branched in the α position or a higherposition. Examples of such radicals are branched C₃-C₂₀-aliphatic,C₉-C₂₀-araliphatic and C₃-C₁₀-cycloaliphatic radicals, e.g. isopropyl,tert-butyl, isobutyl, neopentyl, 2-methyl-2-phenylpropyl (neophyl),cyclohexyl, 1-methylcyclohexyl, bicyclo[2.2.1]hept-2-yl (2-norbornyl),bicyclo[2.2.1]hept-1-yl (1-norbornyl), adamantyl. Further suitableradicals of this type are organosilicon radicals having from three tothirty carbon atoms, for example trimethylsilyl, triethylsilyl,triphenylsilyl, tert-butyldimethylsilyl, tritolylsilyl orbis(trimethylsilyl)methyl.

[0077] Preferred aromatic, bulky groups are generally C₆-C₂₀-arylradicals, such as phenyl, 1- or 2-naphththyl or preferably C₁-C₁₀-alkyl-or C₃-C₁₀-cycloalkyl-substituted aromatic radicals such as2,6-dimethylphenyl, 2,6-di-tert-butylphenyl, mesityl.

[0078] Very particularly preferred substituents R¹ and R⁸ are i-propyl,tert-butyl, trimethylsilyl, cyclohexyl, i-butyl, trifluoromethyl,3,5-dimethylphenyl.

[0079] In the preferred substitution pattern, R¹ and R⁸ in formula I areidentical.

[0080] The substituents R² to R⁷ are identical or different and are eachhydrogen, C₁-C₂₀-alkyl, —OR²⁷, —SR²⁷, —N(R²⁷)₂, —P(R²⁷)₂, where R²⁷ areidentical or different and are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl,C₃-C₁₀-cycloalkyl, alkylaryl or Si(R²⁸)₃ where R²⁸ are identical ordifferent and are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl,alkylaryl, 3- to 8-membered cycloalkyl which may in turn bear aC₁-C₁₀-alkyl radical such as methyl, ethyl or propyl as substituent.Examples of such cycloalkyl radicals are cyclopropyl, cyclopentyl,preferably cyclohexyl, norbornyl. The substituents R² to R⁷ may also beC₆-C₁₅-aryl such as phenyl, naphthyl, alkylaryl having from 1 to 10carbon atoms in the alkyl part and from 6 to 20 carbon atoms in the arylpart, e.g. p-tolyl, arylalkyl having from 1 to 10 carbon atoms in thealkyl part and from 6 to 20 carbon atoms in the aryl part, e.g. benzyl,neophyl, or they may be triorganosilyl such as Si(R⁹)₃ where R⁹ areidentical or different and are each C₁-C₂₀-alkyl, C₃-C₁₀-cycloalkyl,C₆-C₁₅-aryl, for example trimethylsilyl, tert-butyldimethylsilyl,triphenylsilyl. The radicals R² to R⁷ may also be connected to oneanother so that adjacent radicals form saturated, partially saturated orunsaturated cyclic groups having from 4 to 15 carbon atoms. Preferably,the radicals R³ and R⁴ and/or the radicals R⁵ and R⁶ are joined by a C₂bridge so as to form a benzo-fused ring system (naphthyl derivative).The abovementioned radicals R² to R⁷ can, of course, also be partiallyor fully substituted by heteroatoms, for example by S-, N-, O- orhalogen-containing structural elements. Examples of such substitutedradicals R² to R⁷ are the trifluoromethyl, pentafluoroethyl,heptafluoropropyl, heptafluoroisopropyl and pentafluorophenyl groups.

[0081] Particular preference is given to the radicals R² and R⁷ beingidentical and each being hydrogen and R³, R⁴, R⁵, R⁶ each being asdefined above.

[0082] Possible bridging elements Y, Y¹ are the following:

[0083] ═BR¹², ═AlR¹², —Ge—, —Sn—, —O—, —S—, ═SO, ═SO₂, ═NR¹², ═CO, ═PR¹²or ═P(O)R¹²,

[0084] where

[0085] R¹² are identical or different and are each a hydrogen atom, ahalogen atom, a C₁-C₁₀-alkyl group, a C₁-C₁₀-fluoroalkyl group, aC₆-C₁₀-fluoroaryl group, a C₆-C₁₀-aryl group, a C₁-C₁₀-alkoxy group, aC₂-C₁₀-alkenyl group, a C₇-C₄₀-arylalkyl group, a C₈-C₄₀-arylalkenylgroup or a C₇-C₄₀-alkylaryl group or R¹² and R¹³ or R¹² and R¹⁴, in eachcase together with the atoms connecting them, form a ring,

[0086] M¹ is silicon, germanium or tin.

[0087] A ring structure in (I) (m ≠0) is of advantage for the process ofthe invention, and ring sizes where m=1 to 3 are preferred.

[0088] Preferred bridging elements Y, Y¹ are methylene —CH₂—, S, O,—C(CH₃)₂—, where m in formula I is preferably 1 or 2; Y¹ are veryparticularly preferably identical and are each oxygen —O—. Preference isalso given to phenoxide-type structures in which m in formula I is 0,i.e. the aromatic ring systems are linked directly to one another,preferably to form a biphenol derivative.

[0089] Among the unbridged transition metal-aromatic complexes of theformula I which can be used according to the present invention,preference is given to those in which Y represents radicals R′ and R″which are identical or different and are each fluorine, chlorine,bromine, iodine, —OR²⁷, —SR²⁷, —N(R²⁷)₂, —P(R²⁷)₂, where R²⁷ areidentical or different and are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl,C₃-C₁₀-cycloalkyl, alkylaryl or Si(R²⁸)₃ where R²⁸ are identical ordifferent and are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl,alkylaryl, C₁-C₂₀-alkyl or 3- to 8-membered cycloalkyl which may in turnbear a C₁-C₁₀-alkyl radical such as methyl, ethyl or propyl assubstituent. Examples of such cycloalkyl radicals are cyclopropyl,cyclopentyl, preferably cyclohexyl, norbornyl. The substituents R′ andR″ may also be C₆-C₁₅-aryl such as phenyl, naphthyl; alkylaryl havingfrom 1 to 10 carbon atoms in the alkyl part and from 6 to 20 carbonatoms in the aryl part, e.g. p-tolyl; arylalkyl having from 1 to 10carbon atoms in the alkyl part and from 6 to 20 carbon atoms in the arylpart, e.g. benzyl, neophyl, or they may be triorganosilyl such asSi(R⁹)₃ where R⁹ are identical or different and are each C₁-C₂₀-alkyl,C₃-C₁₀-cycloalkyl, C₆-C₁₅-aryl, for example trimethylsilyl,tert-butyldimethylsilyl, triphenylsilyl. The radicals mentioned can, ofcourse, also be partially or fully substituted by heteroatoms, forexample by S-, N-, O- or halogen-containing structural elements.Examples of such substituted radicals R′ and R″ are the trifluoromethyl,pentafluoroethyl, heptafluoropropyl, heptafluoroisopropyl andpentafluorophenyl groups.

[0090] R′ and R′ are preferably identical. Particularly preferredunbridged transition metal-aromatic complexes are ones in which R¹, R⁸,R′ and R″ are identical; a very particularly preferred substitutionpattern is one in which R¹, R³, R′ and R⁶, R⁸, R″ are H and R², R⁴ andR⁵, R⁷ are as defined above, preferably tert-butyl, but are not H. Thephenolic group in (I) is preferably a biphenoxide group having theabove-described substitution pattern.

[0091] The bridged or unbridged transition metal-aromatic complexes Iare generally prepared by methods known to those skilled in the art.

[0092] The synthesis of bridged transition metal phenoxide complexes isdescribed, for example, in C. J. Schaverien, J. Am. Chem. Soc. (1995),pages 3008 to 3012. Another procedure which has been found to be usefulis the following, where the reaction is generally carried out at from−78 to 110° C., preferably initially at about 20° C. and then underreflux to complete the reaction. The biphenol is firstly deprotonated ina solvent, for example tetrahydrofuran (THF), for example using sodiumhydride or n-butyllithium, and the transition metal compound, forexample the halide, e.g. titanium, zirconium or hafnium tetrachloride,advantageously in the form of the bis-THF adduct, is then added. Afterthe reaction is complete, the product is generally obtained byseparating off salts and then crystallizing it. The preparation ofunbridged transition metal phenoxide complexes can be carried out, forexample, as described by H. Yasuda et al., J. Organomet. Chem. 473(1994), pages 105 to 116.

[0093] The bridged or unbridged transition metal-aromatic complexes Igenerally additionally contain from 1 to 4 equivalents of a Lewis basewhich is generally introduced via the synthetic route. Examples of suchLewis bases are ethers such as diethyl ether or tetrahydrofuran (THF) oramines such as TMEDA. However, it is also possible to obtain thetransition metal-aromatic complexes in a form free of Lewis bases, forexample by drying under reduced pressure or by choice of other solventsin the synthesis. Such measures are known to those skilled in the art.

[0094] The racemic metallocene complexes of the present invention areprepared by reacting the bridged or unbridged transition metal-aromaticcomplexes I with cyclopentadienyl derivatives of alkali metals oralkaline earth metals and subsequently heating the resulting reactionmixture in the presence or absence of free radicals or free radicalformers, as described below.

[0095] Preference is given to using transition metal-aromatic complexesI in which M is zirconium and the radicals R¹ and R⁸ have the preferredmeanings described above. Very well-suited complexes aredichlorobis(3,5-di-tert-butylphenolato)zirconium•(THF)₂,dichlorobis(3,5-di-tert-butylphenolato)zirconium•(DME),dichlorobis(2,6-dimethylphenolato)zirconium•(THF)₂,dichlorobis(2,6-dimethylphenolato)zirconium•(DME),dichlorobis(2,4,6-trimethylphenolato)zirconium•(THF)₂,dichlorobis(2,4,6-trimethylphenolato)zirconium•(DME) and the zirconiumphenoxide compounds mentioned in the example.

[0096] Suitable cyclopentadienyl derivatives of alkali metals oralkaline earth metals are in principle those which, after reaction withthe bridged transition metal-aromatic complexes I used according to thepresent invention, selectively give racemic metallocene complexes whichare virtually free of meso isomer.

[0097] The racemic metallocene complexes of the present invention can bebridged, but do not have to be. In general, a high barrier to rotation,especially in the temperature range from 20 to 80° C., (able to bedetermined by ¹H- and/or ¹³C-NMR spectroscopy) of the unbridgedcyclopentadienyl-type ligands in the metallocene is sufficient for themetallocene complexes to be able to be isolated in their racemic formwithout them being able to transform into the meso form. The barrier torotation which ensures this is usually above 20 kJ/mol.

[0098] Well-suited cyclopentadienyl derivatives of alkali metals oralkaline earth metals are those of the formula II

[0099] where the substituents and indices have the following meanings:

[0100] M² is Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba,

[0101] R¹³ to R¹⁷ are identical or different and are each hydrogen,C₁-C₂₀-alkyl, 5- to 7-membered cycloalkyl which may in turn bear aC₁-C₁₀-alkyl group as substituent, C₆-C₁₅-aryl or arylalkyl, whereadjacent radicals may together form cyclic groups having from 4 to 15carbon atoms, or Si(R¹⁸)₃ where

[0102] R¹⁸ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl or C₃-C₁₀-cycloalkyl,

[0103] where the radicals

[0104] R¹⁹ to R²³ are identical or different and are each hydrogen,C₁-C₂₀-alkyl, 5- to 7-membered cycloalkyl which may in turn bear aC₁-C₁₀-alkyl group as substituent, C₆-C₁₅-aryl or arylalkyl, whereadjacent radicals may together form cyclic groups having from 4 to 15carbon atoms, or Si(R²⁴)₃ where

[0105] R²⁴ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl or C₃-C₁₀-cycloalkyl,

[0106] or

[0107] R¹⁶ and Z together form a —[T(R²⁵)(R²⁶)]_(n)—E— group in which

[0108] T may be identical or different and are each silicon, germanium,tin or carbon,

[0109] R²⁵, R²⁶ are each hydrogen, C₁-C₁₀-alkyl, C₃-C₁₀-cycloalkyl orC₆-C₁₅-aryl

[0110] n is 1, 2, 3 or 4,

[0111] where R²⁷ is C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl,alkylaryl or Si(R²⁸)₃

[0112] where R²⁸ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl or alkylaryl,

[0113] where p=1 for Be, Mg, Ca, Sr, Ba and p=2 for Li, Na, K, Rb, Cs.

[0114] Preferred compounds of the formula II are those in which M² islithium, sodium or, in particular magnesium. Particular preference isalso given to compounds of the formula II a)

[0115] in which M² is magnesium, R¹⁷ and R²³ are substituents other thanhydrogen, e.g. C₁-C₁₀-alkyl, such as methyl, ethyl, n-propyl, i-propyl,n-butyl, sec-butyl, tert-butyl, i-butyl, hexyl, also C₆-C₁₀-aryl such asphenyl or trialkylsilyl such as trimethylsilyl, T(R²⁵R²⁶) isbis-C₁-C₁₀-alkylsilyl or bis-C₆-C₁₀-arylsilyl such as dimethylsilyl,diphenylsilyl, also 1,2-ethanediyl, methylene, and the radicals R¹³ toR¹⁵ and R¹⁹ to R²⁵ are as defined above and in particular form anindenyl-type ring system or a benzoindenyl-type ring system.

[0116] Very particularly preferred compounds II are those which aredescribed in the examples and also

[0117]dimethylsilanediylbis(3-tert-butyl-5-methylcyclopentadienyl)magnesium

[0118]diethylsilanediylbis(3-tert-butyl-5-methylcyclopentadienyl)magnesium

[0119]dimethylsilanediylbis(3-tert-butyl-5-ethylcyclopentadienyl)magnesium

[0120]dimethylsilanediylbis(3-tert-pentyl-5-methylcyclopentadienyl)magnesium

[0121] dimethylsilanediylbis(2,4,7-trimethylindenyl)magnesium

[0122] 1,2-ethanediylbis(l-{2,4,7-trimethylindenyl})magnesium

[0123] dimethylsilanediylbis(1-indenyl)magnesium

[0124] dimethylsilanediylbis(4,5,6,7-tetrahydro-1-indenyl)magnesium

[0125] dimethylsilanediylbis(2-methylindenyl)magnesium

[0126] phenyl(methyl)silanediylbis(2-methylindenyl)magnesium

[0127] diphenylsilanediylbis(2-methylindenyl)magnesium

[0128]dimethylsilanediylbis(2-methyl-4,5,6,7-tetrahydro-1-indenyl)magnesium

[0129] dimethylsilanediylbis(2,4-dimethyl-6-isopropylindenyl)magnesium

[0130] dimethylsilanediylbis(2-methyl-1-benzindenyl)magnesium

[0131] dimethylsilanediylbis(2-ethyl-1-benzindenyl)magnesium

[0132] dimethylsilanediylbis(2-propyl-1-benzindenyl)magnesium

[0133] dimethylsilanediylbis(2-phenyl-1-benzindenyl)magnesium

[0134] diphenylsilanediylbis(2-methyl-1-benzindenyl)magnesium

[0135] phenylmethylsilanediylbis(2-methyl-1-benzindenyl)magnesium

[0136] ethanediylbis(2-methyl-1-benzindenyl)magnesium

[0137] dimethylsilanediylbis(2-methyl-1-tetrahydrobenzindenyl)magnesium

[0138] dimethylsilanediylbis(2-methyl-4-isopropyl-1-indenyl)magnesium

[0139] dimethylsilanediylbis(2-methyl-4-phenyl-1-indenyl)magnesium

[0140] dimethylsilanediylbis(2-methyl-4-naphthyl-1-indenyl)magnesium

[0141]dimethylsilanediylbis(2-methyl-4-{3,5-trifluoromethyl}phenyl-1-indenyl)magnesium

[0142] dimethylsilanediylbis(2-ethyl-4-isopropyl-1-indenyl)magnesium

[0143] dimethylsilanediylbis(2-ethyl-4-phenyl-1-indenyl)magnesium

[0144] dimethylsilanediylbis(2-ethyl-4-naphthyl-1-indenyl)magnesium

[0145]dimethylsilanediylbis(2-ethyl-4-{3,5-trifluoromethyl}phenyl-1-indenyl)magnesium

[0146] ethanediylbis(2-methyl-4-phenyl-1-indenyl)magnesium

[0147] ethanediylbis(2-methyl-4-naphthyl-1-indenyl)magnesium

[0148]ethanediylbis(2-methyl-4-{3,5-di-(trifluoromethyl)}phenyl-1-indenyl)magnesium

[0149]dimethylsilanediylbis(2-methyl-4-(4′-tert-butylphenyl)indenyl)magnesium

[0150]dimethylsilanediylbis(2-methyl-4-(4′-tert-butylphenyl)-indenyl)-(2-isopropyl-4-(4′-tert-butylphenyl)indenyl)magnesium

[0151] dimethylsilanediylbis(2-cyclohexyl-4-phenylindenyl)magnesium

[0152] dimethylsilanediylbis(2-butyl-4-phenylindenyl)magnesium

[0153]dimethylsilanediylbis(2-ethyl-4-(4′-tert-butylphenyl)indenyl)magnesium

[0154]dimethylsilanediylbis(2-propyl-4-(4′-tert-butylphenyl)indenyl)magnesium

[0155]dimethylgermanediylbis(2-meth-4-(4′-tert-butylphenyl)indenyl)magnesium

[0156]diethylsilanediylbis(2-methyl-4-(4′-tert-butylphenyl)indenyl)magnesium

[0157]dimethylsilanediylbis(2-butyl-4-(4′-tert-butylphenyl)indenyl)magnesium

[0158]dimethylsilanediyl(2-methyl-4-(4′-tert-butylphenyl)indenyl)-(4-(4′-tert-butylphenyl)indenyl)magnesium

[0159]dimethylsilanediylbis(2-butyl-4-(4′-tert-butylphenyl-6-(4′-tert-butylphenyl)indenyl)magnesium

[0160]dimethylsilanediylbis(2-isopropyl-4-(4′-tert-butylphenyl)indenyl)magnesium

[0161]dimethylsilanediylbis(2-isopropyl-4-(4′-tert-butylphenyl)indenyl)magnesium

[0162]dimethylsilanediyl(2-ethyl-4-(4′-tert-butylphenyl)indenyl)-2-isopropyl-4-(4′-tert.-butylphenyl)indenyl)magnesium

[0163]dimethylsilanediyl(2-methyl-4-naphthylindenyl)-(2-isopropyl-4-(4′-tert-butylphenyl)indenyl)magnesium

[0164] and the respective Lewis base adducts of these compounds with,for example, THF, DME, TMEDA.

[0165] Such alkali or alkaline earth metal compounds II can be obtainedby methods known from the literature, for example by the, preferably,stoichiometric, reaction of an organometallic compound or a hydride ofthe alkali metal or alkaline earth metal with the appropriatecyclopentadiene-type hydrocarbon. Suitable organometallic compounds are,for example, n-butyllithium, di-n-butylmagnesium or(n,s)-dibutylmagnesium (Bomag).

[0166] The reaction of the bridged or unbridged transitionmetal-aromatic complexes I with the cyclopentadienyl derivatives ofalkali or alkaline earth metals, preferably of the formulae II or II a)usually takes place in an organic solvent or suspension medium,preferably in a solvent mixture comprising a Lewis-basic solvent, atfrom −78° C. to 250° C., preferably from 0 to 110° C. Well-suitedsolvents are aliphatic hydrocarbons such as pentane, hexane, heptane,aromatic hydrocarbons such as toluene, ortho-, meta- or para-xylene orisopropylbenzene (cumene), ethers such as tetrahydrofuran (THF), diethylether, methyl tert-butyl ether or dimethoxyethane (DME), amines such asdiisopropylamine, tetramethylethanediamine (TMEDA) or pyridine.Well-suited solvent mixtures are mixtures of toluene and THF, tolueneand DME or toluene and TMEDA, where the Lewis base is generally presentin an amount of from 0.1 to 50 mol %, preferably from 1 to 20 mol %,based on the solvent mixture. The molar ratio of the transitionmetal-aromatic complex I to the cyclopentadienyl derivative of an alkalior alkaline earth metal is usually in the range from 0.8:1 to 1:1.2 andis preferably 1:1.

[0167] It has been found that subsequent warming or heating of thereaction mixture to temperatures in the range from −78 to 250° C.,preferably from 20 to 150° C. and in particular from 80 to 110° C., inthe presence or absence of free radicals or free radical formers quicklyleads to a higher yield, generally from 80 to 100%, preferably from 95to 100%, of racemic complexes (I). Possible free radicals are oxygen and2,2′-6,6′-tetramethylpyrimidine N-oxide (TEMPO). As free radicalformers, it is possible to use all organic and inorganic compounds whichdecompose to generate free radicals in the abovementioned temperaturerange and/or on irradiation, for example peroxides, diacyl peroxides(e.g. benzoyl peroxide, acetyl peroxide), peroxydicarbonates, peresters,azoalkanes, nitrites, hypochlorites, polyhalomethanes, N-chloroamines.Particular preference is given to using TEMPO. Preference is given tousing free radical formers when the metallocene (I) contains abenzo-fused indenyl system such asdimethylsilylbis(2-methylbenzoindenyl) as cyclopentadienyl-type ligand.

[0168] The racemic metallocene complexes prepared according to thepresent invention are preferably complexes of the formula III

[0169] where the substituents and indices have the following meanings:

[0170] M is titanium, zirconium, hafnium, vanadium, niobium, tantalum,chromium, molybdenum, tungsten or an element of transition group III ofthe Periodic Table or a lanthanide,

[0171] X¹

[0172] where:

[0173] R¹, R⁸ are identical or different and are each hydrogen,fluorine, chlorine, bromine, iodine, C₁-C₂₀-alkyl, 3- to 8-memberedcycloalkyl which may in turn bear a C₁-C₁₀-alkyl group as substituent,C₆-C₁₅-aryl, alkylaryl having from 1 to 10 carbon atoms in the alkylpart and from 6 to 20 carbon atoms in the aryl part, arylalkyl havingfrom 1 to 10 carbon atoms in the alkyl part and from 6 to 20 carbonatoms in the aryl part, Si(R⁹)₃ where R⁹ are identical or different andare each C₁-C₂₀-alkyl, C₃-C₁₀-cycloalkyl, C₆-C₁₅-aryl, where theradicals mentioned may be partially or fully substituted by heteroatoms,—OR²⁷, —SR²⁷, —N(R²⁷)₂, —P(R²⁷)₂, where R²⁷ are identical or differentand are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl orSi(R²⁸)₃ where R²⁸ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl

[0174] R² to R⁷ are identical or different and are each hydrogen,C₁-C₂₀-alkyl, 3- to 8-membered cycloalkyl which may in turn bear aC₁-C₁₀-alkyl radical as substituent, C₆-C₁₅-aryl, alkylaryl having from1 to 10 carbon atoms in the alkyl part and from 6 to 20 carbon atoms inthe aryl part, arylalkyl having from 1 to 10 carbon atoms in the alkylpart and from 6 to 20 carbon atoms in the aryl part, Si(R⁹)₃ where R⁹are identical or different and are each C₁-C₂₀-alkyl, C₃-C₁₀-cycloalkyl,C₆-C₁₅-aryl, where adjacent radicals R² to R⁷ may form saturated,partially saturated or unsaturated cyclic groups having from 4 to 15carbon atoms, and the radicals mentioned may be fully or partiallysubstituted by heteroatoms, —OR²⁷, —SR²⁷, —N(R²⁷)₂, —P(R²⁷)₂, where R²⁷are identical or different and are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl,C₃-C₁₀-cycloalkyl, alkylaryl or Si(R²⁸)₃ where R²⁸ are identical ordifferent and are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl,alkylaryl

[0175] Y, Y¹ are identical or different and are each

[0176]  ═BR¹², ═AlR¹², —Ge—, —Sn—, —O—, —S—, ═SO, ═SO₂, ═NR¹², ═CO,═PR¹² or ═P(O)R¹²,

[0177] where

[0178] R¹² are identical or different and are each hydrogen, halogen,C₁-C₁₀-alkyl, C₁-C₁₀-fluoroalkyl, C₆-C₁₀-fluoroaryl, C₆-C₁₀-aryl,C₁-C₁₀-alkoxy, C₂-C₁₀-alkenyl, C₇-C₄₀-arylalkyl, C₈-C₄₀-arylalkenyl,C₇-C₄₀-alkylaryl, or two radicals R¹² together with the atoms connectingthem form a ring,

[0179] M¹ is silicon, germanium or tin and

[0180] m is 0, 1, 2, 3,

[0181] or Y is nonbridging and represents two radicals R′ and R″, where

[0182] R′ and R″ are identical or different and are each hydrogen,fluorine, chlorine, bromine, iodine, C₁-C₂₀-alkyl, 3- to 8-memberedcycloalkyl which may in turn bear a C₁-C₁₀-alkyl group as substituent,C₆-C₁₅-aryl, alkylaryl having from 1 to 10 carbon atoms in the alkylpart and from 6 to 20 carbon atoms in the aryl part, arylalkyl havingfrom 1 to 10 carbon atoms in the alkyl part and from 6 to 20 carbonatoms in the aryl part, Si(R⁹)₃ where R⁹ are identical or different andare each C₁-C₂₀-alkyl, C₃-C₁₀-cycloalkyl, C₆-C₁₅-aryl or together withadjacent radicals R⁴ or R⁵ form saturated, partially saturated orunsaturated cyclic groups having from 4 to 15 carbon atoms, and theradicals mentioned may be fully or partially substituted by heteroatoms,—OR²⁷, —SR²⁷, —N(R²⁷)₂, —P(R²⁷)₂, where R²⁷ are identical or differentand are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl orSi(R²⁸)₃ where R²⁸ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl

[0183] R¹³ to R¹⁷ are identical or different and are each hydrogen,C₁-C₂₀-alkyl, 5- to 7-membered cycloalkyl which may in turn bear aC₁-C₁₀-alkyl group as substituent, C₆-C₁₅-aryl or arylalkyl, whereadjacent radicals may together form cyclic groups having from 4 to 15carbon atoms, or Si(R¹⁸)₃ where

[0184] R¹⁸ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl or C₃-C₁₀-cycloalkyl,

[0185] Z is

[0186]  where the radicals

[0187] R¹⁹ to R²³ are identical or different and are each hydrogen,C₁-C₂₀-alkyl, 5- to 7-membered cycloalkyl which may in turn bear aC₁-C₁₀-alkyl group as substituent, C₆-C₁₅-aryl or arylalkyl, whereadjacent radicals may together form cyclic groups having from 4 to 15carbon atoms or Si(R²⁴)₃ where

[0188] R²⁴ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl or C₃-C₁₀-cycloalkyl,

[0189] or

[0190] R¹⁶ and Z together form a —[T(R²⁵)(R²⁶)]_(q)—E— group in which

[0191] T may be identical or different and are each silicon, germanium,tin or carbon,

[0192] R²⁵, R²⁶ are each hydrogen, C₁-C₁₀-alkyl, C₃-C₁₀-cycloalkyl orC₆-C₁₅-aryl

[0193] q is 1, 2, 3 or 4,

[0194] E is

[0195] where R²⁷ is C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl,alkylaryl or Si(R²⁸)₃

[0196] where R²⁸ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl or alkylaryl.

[0197] Preferred compounds of the formula III are those in which M istitanium, hafnium or, in particular, zirconium. Furthermore, particularpreference is given to bridged compounds of the formula III (ansametallocenes) in which R¹⁷ and R²³ are substituents other than hydrogen,for example C₁-C₁₀-alkyl such as methyl, ethyl, n-propyl, i-propyl,n-butyl, sec-butyl, tert-butyl, i-butyl, hexyl, also C₆-C₁₀-aryl such asphenyl or trialkylsilyl such as trimethylsilyl, T(R²⁵R²⁶) isbis-C₁-C₁₀-alkylsilyl or bis-C₆-C₁₀-arylsilyl such as dimethylsilyl,diphenylsilyl, also 1,2-ethanediyl, methylene, and the radicals R¹³ toR¹⁵ and R¹⁹ to R²⁵ are as defined above and in particular form anindenyl-type ring system or a benzoindenyl-type ring system.

[0198] Very particularly preferred compounds III are those which aredescribed in the examples, and also

[0199]dimethylsilanediylbis(3-tert-butyl-5-methylcyclopentadienyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0200]diethylsilanediylbis(3-tert-butyl-5-methylcyclopentadienyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0201]dimethylsilanediylbis(3-tert-butyl-5-ethylcyclopentadienyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0202]dimethylsilanediylbis(3-tert-pentyl-5-methylcyclopentadienyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0203] dimethylsilanediylbis(2,4,7-trimethylindenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0204] 1,2-ethanediylbis(1-{2,4,7-trimethylindenyl})zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0205] dimethylsilanediylbis(1-indenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0206] dimethylsilanediylbis(4,5,6,7-tetrahydro-1-indenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0207] dimethylsilanediylbis(2-methylindenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0208] phenyl(methyl)silanediylbis(2-methylindenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0209] diphenylsilanediylbis(2-methylindenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0210]dimethylsilanediylbis(2-methyl-4,5,6,7-tetrahydro-1-indenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0211] dimethylsilanediylbis(2,4-dimethyl-6-isopropylindenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0212] dimethylsilanediylbis(2-methyl-1-benzindenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0213] dimethylsilanediylbis(2-ethyl-1-benzindenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0214] dimethylsilanediylbis(2-propyl-1-benzindenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0215] dimethylsilanediylbis(2-phenyl-1-benzindenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0216] diphenylsilanediylbis(2-methyl-1-benzindenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0217] phenylmethylsilanediylbis(2-methyl-1-benzindenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0218] ethanediylbis(2-methyl-1-benzindenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0219] dimethylsilanediylbis(2-methyl-1-tetrahydrobenzindenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0220] dimethylsilanediylbis(2-methyl-4-isopropyl-1-indenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0221] dimethylsilanediylbis(2-methyl-4-phenyl-1-indenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0222] dimethylsilanediylbis(2-methyl-4-naphthyl-1-indenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0223]dimethylsilanediylbis(2-methyl-4-{3,5-trifluoromethyl}phenyl-1-indenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0224] dimethylsilanediylbis(2-ethyl-4-isopropyl-1-indenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0225] dimethylsilanediylbis(2-ethyl-4-phenyl-1-indenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0226] dimethylsilanediylbis(2-ethyl-4-naphthyl-1-indenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0227]dimethylsilanediylbis(2-ethyl-4-{3,5-trifluoromethyl}phenyl-1-indenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0228] ethanediylbis(2-methyl-4-phenyl-1-indenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0229] ethanediylbis(2-methyl-4-naphthyl-1-indenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0230]ethanediylbis(2-methyl-4-{3,5-di-(trifluoromethyl)}phenyl-1-indenyl)zirconium3,3′,5,5′-tetra-t-butyl-1,1′-bi-2-phenoxide

[0231]dimethylsilanediylbis(2-methyl-4-(4′-tert-butylphenyl)indenyl)zirconium3,3′,5,5′-tetra-tBu-1,1′-bi-2-phenoxide

[0232]dimethylsilanediyl(2-methyl-4-(4′-tert-butylphenyl)indenyl)(2-isopropyl-4-(4′-tert-butylphenyl)indenyl)zirconium3,3′,5,5′-tetra-tBu-1,1′-bi-2-phenoxide

[0233] dimethylsilanediylbis(2-cyclohexyl-4-phenylindenyl)zirconium3,3′5,5′-tetra-tBu-1,1′-bi-2-phenoxide

[0234] dimethylsilanediylbis(2-butyl-4-phenyl-indenyl)zirconium3,3′5,5′-tetra-tBu-1,1′-bi-2-phenoxide

[0235]dimethylsilanediylbis(2-ethyl-4-(4′-tert-butylphenyl)indenyl)zirconium3,3′5,5′-tetra-tBu-1,1′-bi-2-phenoxide

[0236]dimethylsilanediylbis(2-propyl-4-(4′-tert-butylphenyl)indenyl)zirconium3,3′5,5′-tetra-tBu-1,1′-bi-2-phenoxide

[0237]dimethylgermanediylbis(2-methyl-4-(4′-tert-butylphenyl)indenyl)zirconium3,3′5,5′-tetra-tBu-1,1′-bi-2-phenoxide

[0238]diethylsilanediylbis(2-methyl-4-(4′-tert-butylphenyl)indenyl)zirconium3,3′5,5′-tetra-tBu-1,1′-bi-2-phenoxide

[0239]dimethylsilanediylbis(2-butyl-4-(4′-tert-butylphenyl)indenyl)zirconium3,3′5,5′-tetra-tBu-1,1′-bi-2-phenoxide

[0240]dimethylsilanediyl(2-methyl-4-(4′-tert-butylphenyl)indenyl)-4-(4′-tert-butylphenyl)indenyl)zirconium3,3′5,5′-tetra-tBu-1,1′-bi-2-phenoxide

[0241]dimethylsilanediylbis(2-butyl-4-(4′-tert-butylphenyl)-6-(4′-tert-butylphenyl)indenyl)zirconium3,3′5,5′-tetra-tBu-1,1′-bi-2-phenoxide

[0242]dimethylsilanediylbis(2-isopropyl-4-(4′-tert-butylphenyl)indenyl)zirconium3,3′5,5′-tetra-tBu-1,1′-bi-2-phenoxide

[0243]dimethylsilanediyl(2-ethyl-4-(4′-tert-butylphenyl)indenyl)(2-isopropyl-4-(4′-tert-butylphenyl)indenyl)zirconium3,3′5,5′-tetra-tBu-1,1′-bi-2-phenoxide

[0244]dimethylsilanediyl(2-methyl-4-naphthylindenyl)-(2-isopropyl-4-(4′-tert-butylphenyl)indenyl)zirconium3,3′5,5′-tetra-tBu-1,1′-bi-2-phenoxide

[0245] The racemic metallocene complexes, preferably those of theformula III, can generally be modified further.

[0246] In particular, a bridged biphenoxide ligand X¹ in the complex IIIcan be completely or half split or one or both unbridged phenoxideligands can be split off by monosubstitution or disubstitution and, ifdesired, used further. Suitable splitting-off (replacement) methods arereaction of the racemic metallocene compounds, preferably those of theformula III, with SOCl₂, silicon tetrachloride, methylaluminumdichloride, dimethylaluminum chloride, aluminum trichloride or aBrönsted acid such as a hydrogen halide, i.e. HF, HBr, HI, preferablyHCl, which is generally used as such or as a solution in water ororganic solvents such as diethyl ether or THF. Well-suited solvents arealiphatic hydrocarbons such as pentane, hexane, heptane, aromatichydrocarbons such as toluene, ortho-, meta- or para-xylene orisopropylbenzene (cumene), ethers such as tetrahydrofuran (THF), diethylether, methyl tert-butyl ether or dimethoxyethane (DME), amines such asdiisopropylamine, tetramethylethanediamine (TMEDA) or pyridine. Verywell-suited solvents are Lewis-base-containing mixtures of hydrocarbonsand ethers or amines or both, for example mixtures of toluene and THF,toluene and DME or toluene and TMEDA, where the Lewis base is generallypresent in an amount of 0.01-50 mol %, preferably 0.1-10 mol %, based onthe solvent mixture. Particularly useful “replacement reagents” arecarboxylic halides such as acetyl chloride, phenylacetyl chloride,2-thiophenacetyl chloride, trichloroacetyl chloride, trimethylacetylchloride, O-acetylmandeloyl chloride, 1,3,5-benzenetricarboxylicchloride, 2,6-pyridinecarboxylic chloride, tert-butylacetyl chloride,chloroacetyl chloride, 4-chlorophenylacetyl chloride, dichloroacetylchloride, 3-methoxyphenylacetyl chloride, acetyl bromide, bromoacetylbromide, acetyl fluoride, benzoyl fluoride, which are generally used inthe abovementioned solvents or as such. This usually gives the dihalideanalogous to the formula III (X=F, Cl, Br, I) or, in the case of partial(half) replacement of the phenolic ligand, a monohalide. A furtherwell-suited replacement method is reaction of the racemic metallocenecomplexes, preferably those of the formula III, with organoaluminumcompounds such as tri-C₁-C₁₀-alkylaluminum, e.g. trimethylaluminum,triethylaluminum, tri-n-butylaluminum, triisobutylaluminum. Thisgenerally gives, on the basis of present knowledge, the organo compoundanalogous to III (X=organic radical, e.g. C₁-C₁₀-alkyl such as methyl,ethyl, n-butyl, i-butyl) and, for example, the organoaluminumbinaphthoxide. An analogous method can also be used when the ligand X¹in the complex III is two unbridged phenoxide ligands.

[0247] In the cleavage reactions, the components are usually used in thestoichiometric ratio regardless of whether a monosubstituted ordisubstituted product is to be obtained.

[0248] The cleavage reactions generally take place with retention of thestereochemistry of the metallocene complexes, i.e. there is generally noconversion of the racemic form into the meso form of the metallocenecomplexes. Rather, particularly when using the above-describedchlorination methods, the rac-selectivity can be increased whilegenerally retaining the stereochemistry of the starting (bi)phenoxide orstarting bisphenoxide complexes.

[0249] The process of the present invention makes it possible to obtainthe racemic form of metallocene complexes very selectively. Bridgedindenyl-type or benzoindenyl-type metallocenes which have a ligand otherthan hydrogen next to the bridge (namely the 2 position) can be obtainedparticularly advantageously.

[0250] The racemic metal complexes prepared according to the presentinvention, particularly those of the formula III or theirabove-described derivatives obtainable, for example, by replacement ofthe phenoxide ligands, can be used as catalysts or in catalyst systemsfor the polymerization of olefinically unsaturated compounds such asethylene, propylene, 1-butene, 1-hexene, 1-octene or styrene. Their useis particularly advantageous in the stereoselective polymerization ofprochiral, olefinically unsaturated compounds such as propylene orstyrene. Suitable catalysts or catalyst systems in which the racemicmetallocene complexes of the present invention can function as“metallocene component” are usually obtained by means of compoundscapable of forming metallocenium ions, as described, for example, inEP-A-0 700 935, page 7, line 34 to page 8, line 21 and formulae (IV) and(V). Further compounds capable of forming metallocenium ions arealuminoxanes (RAlO)_(n) such as methylaluminoxane.

[0251] The racemic metallocene complexes prepared according to thepresent invention, in particular those of the formula III or theirabove-described derivatives obtainable, for example, by splitting offthe phenoxide ligands, can also be used as reagents or as catalysts orin catalyst systems in stereoselective, in particular organic,synthesis. Examples which may be mentioned are stereoselectivereductions or stereoselective alkylations of C═C double bonds or C═O orC═N double bonds.

EXAMPLES

[0252] Abbreviations:

[0253] bpo=1,1′-bi-2-phenoxide

[0254] bip =3,3′,5,5′-tetra-t-Bu-1,1′-bi-2-phenoxide

Examples in Which rac-Selectivity is Achieved by Thermal Isomerization

[0255] Example 1

[0256] Preparation ofrac-Me₂Si(2-Me-ind)₂Zr[3,3′,5,5′-(t-Bu)₄-1,1′-bi-2-phenoxide]

[0257] (rac-Me₂Si(2-Me-ind)₂Zr(bip) (4C)

[0258] 0.64 g (1.95 mmol) of Me₂Si(2-Me-ind)₂Li₂ and 1.39 g (1.95 mmol)of Cl₂(THF)₂Zr(bip) were mixed dry and about 15 ml of a 10:1 mixture oftoluene/THF (volume ratio) were added. The reaction mixture was stirredat room temperature for 12 hours. This resulted in formation of anorange solution and a white precipitate (LiCl). The ¹H-NMR spectrum ofthe crude mixture indicated an isomer ratio of about 1:1. The reactionmixture was stirred at 80° C. for 5 hours. The ¹H-NMR spectrum thenindicated an rac/meso ratio of about 16:1. The solution was filtered andthe solvent mixture was removed in a high vacuum. This gave 1.17 g (74%)of Me₂Si(2-Me-ind)₂Zr(bip) as a yellow foam which was pure according toNMR spectroscopy and had an rac/meso ratio of 16:1. The yellow foam wastaken up in hexane and cooled to −30° C. After one day, filtration gave0.35 g (22%) of pure racemic Me₂Si(2-Me-ind)₂Zr(bip) as amicrocrystalline yellow powder. ¹H-NMR spectrum in C₆D₆: see Table B.¹³C-NMR spectrum in C₆D₆ (25° C., 600 MHz): 161.1, 141.2, 135.3, 134.8,134.3, 131.8, 130.9, 129.7, 126.0, 126.8, 124.9, 123.3, 121.8, 111.6,92.4, 34.3, 32.5, 32.1, 31.8, 18.8, 2.55. The mass spectrum (EI-MS/70eV) showed the molecular ion peak at m/e 812-821 with the typicalisotope distribution. Elemental analysis: found: C 73.64%; H 7.73%; Zr11.06; calculated: C 73.74%; H 7.67%; Zr 11.20%. TABLE B ¹H-NMR shiftsfor the complex rac-4C (in ppm, C₆D₆, 25° C., 600 MHz) Assignment^(a)7.60 (d, 2H) ³J (8.4 Hz) C₉H₅ (H7, H7′) 7.49 (d, 2H) ⁴J (2.4 Hz) C₆H₂(H4, H4′) 7.26 (d, 2H) ³J (8.4 Hz) C₉H₅ (H4, H4′) 7.18 (d, 2H) ⁴J (2.4Hz) C₆H₂ (H6, H6′) 6.85 (dd, 2H) ³J (8.4 Hz) ³J (7.2 Hz) C₉H₅ (H6, H6′)6.77 (dd, 2H) ³J (8.4 Hz) ³J (7.2 Hz) C₉H₅ (H5, H5′) 5.83 (s, 2H) C₉H₅(H3, H3′) 2.21 (s, 6H) (2—CH₃—C₉H₅) 1.36, 1.33 (s, 18H) (CH₃)₃C 0.80 (s,6H) (CH₃)₂Si

[0259] Example 2

[0260] Synthesis ofMe₂Si(2-Me-ind-4-Ph)₂Zr(3,3′5,5′-tetra-^(t)Bu-1,1′-bi-2-phenoxide)

[0261] (Me₂Si(2-Me-4-Ph-ind)₂Zr(bip)

[0262] A) Synthesis of ZrCl₄(THF)₂

[0263] 3.1 g (43.0 mmol) of THF were slowly added dropwise to asuspension of 4.99 g (21.41 mmol) of ZrCl₄ in 80 ml of toluene at 0° C.(cooling in an ice bath) over a period of 15 minutes. The suspension waswarmed to room temperature and stirred for 1 hour.

[0264] B) Synthesis of (3,3′5,5′-tetra-^(t)Bu-1,1′-bi-2-phenolato)Li₂

[0265] 17.0 ml (45.56 mmol) of a 2.68 molar BuLi solution in toluenewere slowly added dropwise to a solution of 8.79 g (21.4 mmol) of3,3′5,5′-tetra-^(t)Bu-1,1′-bi-2-phenol in 120 ml of toluene and 3.1 g(43.0 mmol) of THF at 0° C. (cooling in an ice bath) over a period of 20minutes. The clear solution was warmed to room temperature and stirredfor 1 hour.

[0266] C) Synthesis ofCl₂Zr(3,3′5,5′-tetra-^(t)Bu-1,1′-bi-2-phenoxide)(THF)₂

[0267] The dilithium biphenoxide solution from subreaction B) was addedunder nitrogen by means of a syringe to the ZrCl₄(THF)₂ suspension fromsubreaction A). Residues of dilithium biphenoxide solution remaining inthe flask were rinsed in using 10 ml of toluene. The suspension wasstirred at room temperature for 4 hours.

[0268] D) Synthesis of Me₂Si(2-Me-4-Ph-ind)₂Li₂

[0269] 16.4 ml (43.95 mmol) of a 2.68 molar BuLi solution in toluenewere slowly added dropwise at room temperature to a solution of 9.8 g(20.90 mmol) of Me₂Si(2-Me-4-Ph-indH)₂ in 110 ml of toluene and 5 g(69.33 mmol) of THF over a period of 20 minutes. The light-yellowsuspension was heated to 60° C., stirred for 1 hour and cooled to roomtemperature.

[0270] E) Synthesis of Me₂Si(2-Me-4-Ph-ind)₂Zr(bip)

[0271] The suspension from C) was added under nitrogen by means of asyringe to the Me₂Si(2-Me-4-Ph-ind)₂Li₂ suspension from substep D) atroom temperature. After the addition was complete, the suspension becameyellow-orange. The reaction mixture was stirred at room temperature for12 hours. A ¹H-NMR spectrum of the reaction mixture indicated anrac-meso ratio of about 1:1. The suspension was heated at 85° C. for 9hours. ¹H-NMR spectroscopic analysis of the crude mixture indicated anrac-meso ratio of about 15:1, without signs of impurities ordecomposition products. The suspension was filtered, the whiteprecipitate was washed with a little toluene and the combined filtrateswere evaporated to about ¼ of their volume in a high vacuum. After somedays, an orange crystalline precipitate formed and this was isolated byfiltration and subsequent drying. 8 g (39.5%) of pure racemicMe₂Si(2-Me-4-Ph-ind)₂Zr(bip) were obtained. Proceeding in an analogousfashion (multiple crystallization) gave a total of 17.1 g (85%) of pureracemic Me₂Si(2-Me-4-Ph-ind)₂Zr(bip).

[0272] Elemental analysis forMe₂Si(2-Me-4-Ph-ind)₂Zr(3,3′-5,5′-tetra-t-Bu-1,1′-bi-2-phenoxide) Found:C: 77.0%; H: 7.4%; calculated: C: 77.0%; H: 7.3%

[0273]¹H-NMR spectrum in C₆D₆: see Table C. TABLE C ¹H-NMR shifts forthe complex (in ppm, C₆D₆ 25° C., 200 MHZ) Assignment 7.78 (d, 2H) H(aromatic) 7.44 (d, 2H) C₆H₂O (bip) 7.34-6.96 (m, 14 H) H (aromatic)6.49 (d, 2H) C₆H₂O (bip) 6.36 (s, 2H) C₅H 2.27 (S, 6H) CH₃ 1.32 (s, 18H)C(CH₃)₃ 1.25 (s, 18H) C(CH₃)₃ 0.99 (s, 6H) Me₂Si

[0274] Example 3

[0275] Synthesis ofMe₂Si(2-Me-4-(4-^(t)Bu-Ph-ind)₂Zr(3,3′5,5′-tetra-^(t)Bu-1,1′-bi-2-phenoxide)

[0276] Me₂Si(2-Me-4-(4-^(t)Bu-Ph)-ind)₂Zr(bip)

[0277] A) Synthesis of ZrCl₄(THF)₂

[0278] 3.8 g (52.7 mmol) of THF were slowly added dropwise to asuspension of 5.45 g (23.38 mmol) of ZrCl₄ in 100 ml of toluene at 0° C.(cooling in an ice bath) over a period of 15 minutes. The suspension waswarmed to room temperature and stirred for 1 hour.

[0279] B) Synthesis of (3,3′5,5′-tetra-^(t)Bu-1,1′-bi-2-phenolato)Li₂

[0280] 18.3 ml (49.1 mmol) of a 2.68 molar BuLi solution in toluene wereslowly added dropwise to a solution of 9.6 g (23.38 mmol) of3,3′5,5′-tetra-^(t)Bu-1,1′-bi-2-phenol in 130 ml of toluene and 3.8 g(52.7 mmol) of THF at 0° C. (cooling in an ice bath) over a period of 20minutes. The clear light-yellow solution was warmed to room temperatureand stirred for 1 hour.

[0281] C) Synthesis ofCl₂Zr(3,3′5,5′-tetra-^(t)Bu-1,1′-bi-2-phenoxide)(THF)₂

[0282] The lithium biphenoxide solution from subreaction B) was addedunder nitrogen by means of a syringe to the ZrCl₄(THF)₂ suspension fromsubreaction A). Residues which remained in the flask were rinsed inusing 10 ml of toluene. The suspension was stirred at room temperaturefor 4 hours.

[0283] D) Synthesis of Me2Si(2-Me-4-(4′-^(t)Bu-Ph)-ind)₂Li₂

[0284] 17.5 ml (46.9 mmol) of a 2.68 molar BuLi solution in toluene wereslowly added dropwise at room temperature to a solution of 13.0 g (22.38mmol) of Me₂Si(2-Me-4-(4′-^(t)Bu-Ph)-indH)₂ in 150 ml of toluene and 6 g(83.20 mmol) of THF over a period of 20 minutes. The light-yellowsuspension was heated to 60° C., stirred for 1 hour and cooled to roomtemperature.

[0285] E) Synthesis of Me₂Si(2-Me-4-(4′-^(t)Bu-Ph)-ind)₂Zr(bip)

[0286] The suspension from C) was added under nitrogen by means of asyringe to the Me2Si(2-Me-4-(4′-^(t)Bu-Ph)-ind)₂Li₂ suspension fromsubstep D) at room temperature. After the addition was complete, thesuspension became yellowish. The reaction mixture was stirred at roomtemperature for 12 hours. A ¹H-NMR spectrum of the reaction mixtureindicated an rac-meso ratio of about 1:2. The suspension was heated at85° C. for 9 hours. The ¹H-NMR spectroscopic analysis of the crudemixture indicated an rac-meso ratio of about 15:1 without signs ofimpurities or decomposition products. The suspension was filtered, thewhite precipitate was washed with a little toluene and the combinedfiltrates were evaporated to about ¼ of their volume in a high vacuum.Repeated crystallization at room temperature, filtration and drying gavea total of 21.1 g (88%) of pure racemicMe₂Si(2-Me-4-(4′-t-Bu-Ph-ind)₂Zr(bip).

[0287]Me₂Si(2-Me-4-(4′-t-Bu-PH)₂Zr(3,3′-5,5′-tetra-t-Bu-1,1′-bi-2-phenoxide)

[0288]¹H-NMR shifts (in ppm, C₆D₆ 25° C., 200 MHz) 7.76 (m, 4H)H_(arom.) 7.76 (m, 4H) H_(arom.) 7.47 (d, 2H) C₆H₂ (biphenol) 7.35-6.95(m, 10H) H_(arom.) 6.56 (d, 2H) C₆H₂ (biphenol) 6.34 (s, 2H) C₅H 2.26(s, 6H) CH₃ 1.33 (s, 18H) (CH₃)₃C 1.28 (s, 18H) (CH₃)₃C 1.27 (s, 18H)(CH₃)₃C 0.99 (s, 6H) Me₂Si

Example in Which rac-Selectivity is Achieved by Addition of Free RadicalSources and Heating (Isomerization)

[0289] Example 4

[0290] Synthesis of rac-Me₂Si(2-Me-benz[e]ind)₂Zr(bip) (5C)

[0291] 0.89 g (2.10 mmol) of Me₂Si(2-Me-benz[e]ind)₂Li₂ and 1.50 g (2.10mmol) of Cl₂(THF)₂Zr(bip) were mixed dry and about 15 ml of a 10:1mixture of toluene/THF (volume ratio) were added. The reaction mixturewas stirred at room temperature for 12 hours. This resulted in formationof an orange solution and a white precipitate (LiCl). The ¹H-NMRspectrum of the crude mixture indicated an isomer ratio of about 1:1.The reaction mixture was filtered. 0.30 g (1.92 mmol) of TEMPO was addedto the filtrate at room temperature and the reaction mixture was heatedat 75° C. for 1 hour. The ¹H-NMR spectrum of the crude mixture indicatedpure racemic Me₂Si(2-Me-benz[e]ind)₂Zr(bip). Concentration of thesolution by evaporation in a high vacuum and multiple crystallization atroom temperature gave a total of 1.6 g (1.76 mmol; 84%) ofrac-Me₂Si(2-Me-benz[e]ind)₂Zr(bip).

[0292]¹H-NMR spectrum in CDCl₃: see Table E. ¹³C-NMR spectrum in CDCl₃(25° C., 600 MHz): 158.1, 139.1, 133.3, 133.1, 131.8, 131.6, 130.1,128.9, 128.2, 127.6, 127.2, 126.4, 125.6, 124.1, 124.0, 121.2, 110.8,97.3, 35.3, 34.0, 33.1, 31.8, 19.1, 2.9. The mass spectrum (EI-MS/70 eV)displays a molecular ion peak at m/e 906-915 with the typical isotopedistribution. Elemental analysis: found: C 75.99% ; H 7.09%; Zr 9.83%;calculated: C 76.18%; H 7.27%; Zr 9.97%. TABLE E ¹H-NMR shifts for thecomplex rac-5C (in ppm, CDCl₃, 25° C., 600 MHz) Assignment^(a) 7.62 (d,2H) ³J (8.5 Hz) C₁₃H₇ (H8/9, H8′/9′) 7.47 (d, 2H) ³J (7.8 Hz) C₁₃H₇ (H7,H7′) 7.19 (d, 2H) ³J (8.5 Hz) C₁₃H₇ (H8/9, H8′/9′) 7.11 (d, 2H) ⁴J (2.5Hz) C₆H₂ (H4/6, H4′/6′) 7.10 (dd, 2H) ³J (7.8 Hz) ³J (7.3 Hz) C₁₃H₇ (H6,H6′) 6.95 (dd, 2H) ³J (7.9 Hz) ³J (7.3 Hz) C₁₃H₇ (H5, H5′) 6.65 (d, 2H)³J (7.9 Hz) C₁₃H₇ (H4, H4′) 6.34 (s, 2H) C₁₃H₇ (H3, H3′) 6.24 (d, 2H) ⁴J(2.5 Hz) C₆H₂ (H4/6, H4′/6′) 2.63 (s, 6H) (2—CH₃—C₁₃H₇) 1.38 (s, 6H)(CH₃)₂Si 1.28, 1.02 (s, 18H) (CH₃)₃C

Examples of the Replacement of Phenoxides on Ansa-metalloceneBisphenoxide Complexes

[0293] Example 5

[0294] Preparation of Me₂Si(2-Me-benz[e]ind)₂ZrCl₂ by Reaction ofMe₂Si(2-Me-benz[e]ind)₂Zr(3,5-Me₂-OC₆H₃)₂ with CH₃COCl

[0295] 0.63 g (8.02 mmol) of acetyl chloride in 13 g of toluene wereadded dropwise at room temperature to a solution of 2.8 g (3.74 mmol) ofrac-Me₂Si(2-Me-benz[e]ind)₂Zr(3,5-Me₂-OC₆H₃)₂ in 48 g of toluene and 0.6g (8.3 mmol) of THF. The solution was stirred at room temperature for 2days. The light-orange solution became increasingly yellow. After somehours, the formation of a light-yellow crystalline precipitate wasobserved. The ¹H-NMR spectrum showed, apart from the resonances of3,5-Me₂-phenyl acetate, signals of pure racemicMe₂Si(2-Me-benz[e]ind)₂ZrCl₂. The light-yellow crystalline precipitatewas isolated by filtration, washed with a little toluene and dried in ahigh vacuum. This gave 1.97 g (3.42 mmol) (92%) of pure racemicMe₂Si(2-Me-benz[e]ind)₂ZrCl₂ in analytically pure form.

[0296] Preparation of Me₂Si(2-Me-benz[e]ind)₂Zr(3,5-Me₂-OC₆H₃)Cl byReaction of Me₂Si(2-Me-benz[e]ind)₂Zr(3,5-Me₂-OC₆H₃)₂ with CH₃COCl

[0297] 0.26 g (3.34 mmol) of acetyl chloride in 10 g of toluene wasadded dropwise at room temperature to a solution of 2.5 g (3.34 mmol) ofrac-Me₂Si(2-Me-benz[e]ind)₂Zr(3,5-Me₂-OC₆H₃)₂ in 60 g of toluene and0.25 g (3.4 mmol) of THF. The solution was stirred at room temperaturefor 2 days. The light-orange solution became increasingly yellow. The¹H-NMR spectrum showed, apart from the resonances of 3,5-Me₂-phenylacetate, signals of pure racemicMe₂Si(2-Me-benz[e]ind)₂Zr(3,5-Me₂-OC₆H₃)Cl. The solution was evaporatedto about ¼ of its volume in a high vacuum. After some days, alight-yellow crystalline precipitate was formed and this was filteredoff, washed with a little toluene and dried in a high vacuum, giving 2.0g (90%) of pure racemic Me₂Si(2-Me-benz[e]ind)₂Zr(3,5-Me₂-OC₆H₃)Cl inanalytically pure form.

[0298] Elemental analysis forMe₂Si(Me-benz[e]ind)₂ZrCl(3,5-di-Me-phenoxide): found: C: 67.5%; H: 5.3;calculated: C: 68.8%; H: 5.3%

[0299] Me₂Si(2-Me-benz[e]ind)₂ZrCl(3,5-di-Me-phenoxide) ¹H-NMR shifts(in ppm, CDCl₃, 25° C., 200 MHz) 7.90 (d, 1H) H_(arom.) 7.78 (d, 1H)H_(arom.) 7.70-6.88 (11m, H) H_(arom.) 6.69 (s, 1H) C₅H or C₆H₃ (4position of phenoxide) 6.33 (s, 1H) C₅H or C₆H₃ (4 position ofphenoxide) 5.81 (s, 2H) C₆H₃ (2,6 positions of phenoxide) 2.29 (s, 3H)CH₃ 2.20 (s, 3H) CH₃ 2.12 (s, 6H) 3,5—(CH₃)₂ (phenoxide) 0.95 (s, 3H)Me₂Si 0.89 (s, 3H) Me₂Si

We claim:
 1. A process for preparing racemic metallocene complexes byreacting bridged or unbridged transition metal-aromatic complexes of theformula I

where the substituents and indices have the following meanings: M istitanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium,molybdenum, tungsten or an element of transition group III of thePeriodic Table or a lanthanide, X are identical or different and areeach fluorine, chlorine, bromine, iodine, hydrogen, C₁-C₁₀-alkyl,C₆-C₁₅-aryl, alkylaryl having from 1 to 10 carbon atoms in the alkylpart and from 6 to 20 carbon atoms in the aryl part, —OR¹⁰ or —NR¹⁰R¹¹,n is an integer from 1 to 4, where n corresponds to the valence of Mminus 2, R¹, R⁸ are identical or different and are each fluorine,chlorine, bromine, iodine, C₁-C₂₀-alkyl, 3- to 8-membered cycloalkylwhich may in turn bear a C₁-C₁₀-alkyl group as substituent, C₆-C₁₅-aryl,alkylaryl having from 1 to 10 carbon atoms in the alkyl part and from 6to 20 carbon atoms in the aryl part, arylalkyl having from 1 to 10carbon atoms in the alkyl part and from 6 to 20 carbon atoms in the arylpart, Si(R⁹)₃ where R⁹ are identical or different and are eachC₁-C₂₀-alkyl, C₃-C₁₀-cycloalkyl, C₆-C₁₅-aryl, where the radicalsmentioned may be partially or fully substituted by heteroatoms, —OR²⁷,—SR²⁷, —N(R²⁷)₂, —P(R²⁷)₂, where R²⁷ are identical or different and areeach C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl or Si(R²⁸)₃where R²⁸ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl R² to R⁷ are identical ordifferent and are each hydrogen, C₁-C₂₀-alkyl, 3- to 8-memberedcycloalkyl which may in turn bear a C₁-C₁₀-alkyl radical as substituent,C₆-C₁₅-aryl, alkylaryl having from 1 to 10 carbon atoms in the alkylpart and from 6 to 20 carbon atoms in the aryl part, arylalkyl havingfrom 1 to 10 carbon atoms in the alkyl part and from 6 to 20 carbonatoms in the aryl part, Si(R⁹)₃ where R⁹ are identical or different andare each C₁-C₂₀-alkyl, C₃-C₁₀-cycloalkyl, C₆-C₁₅-aryl, where adjacentradicals R² to R⁷ may form saturated, partially saturated or unsaturatedcyclic groups having from 4 to 15 carbon atoms, and the radicalsmentioned may be fully or partially substituted by heteroatoms, —OR²⁷,—SR²⁷, —N(R²⁷)₂, —P(R²⁷)₂, where R²⁷ are identical or different and areeach C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl or Si(R²⁸)₃where R²⁸ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl R¹⁰, R¹¹ are eachC₁-C₁₀-alkyl, C₆-C₁₅-aryl, alkylaryl, arylalkyl, fluoroalkyl orfluoroaryl each having from 1 to 10 carbon atoms in the alkyl radicaland from 6 to 20 carbon atoms in the aryl radical, Y, Y¹ are identicalor different and are each

 ═BR¹², ═AlR¹², —Ge—, —Sn—, —O—, —S—, ═SO, ═SO₂, NR¹², ═CO, ═PR¹² or═P(O)R¹², where R¹² are identical or different and are each hydrogen,halogen, C₁-C₁₀-alkyl, C₁-C₁₀-fluoroalkyl, C₆-C₁₀-fluoroaryl,C₆-C₁₀-aryl, C₁-C₁₀-alkoxy, C₂-C₁₀-alkenyl, C₇-C₄₀-arylalkyl,C₈-C₄₀-arylalkenyl, C₇-C₄₀-alkylaryl, or two radicals R¹² together withthe atoms connecting them form a ring, M¹ is silicon, germanium or tinand m is 0, 1, 2, 3, or Y is nonbridging and represents two radicals R′and R″, where R′ and R″ are identical or different and are eachhydrogen, fluorine, chlorine, bromine, iodine, C₁-C₂₀-alkyl, 3- to8-membered cycloalkyl which may in turn bear a C₁-C₁₀-alkyl group assubstituent, C₆-C₁₅-aryl, alkylaryl having from 1 to 10 carbon atoms inthe alkyl part and from 6 to 20 carbon atoms in the aryl part, arylalkylhaving from 1 to 10 carbon atoms in the alkyl part and from 6 to 20carbon atoms in the aryl part, Si(R⁹)₃ where R⁹ are identical ordifferent and are each C₁-C₂₀-alkyl, C₃-C₁₀-cycloalkyl, C₆-C₁₅-aryl ortogether with adjacent radicals R⁴ or R⁵ form saturated, partiallysaturated or unsaturated cyclic groups having from 4 to 15 carbon atoms,and the radicals mentioned may be fully or partially substituted byheteroatoms, —OR²⁷, —SR²⁷, —N(R²⁷)₂, —P(R²⁷)₂, where R²⁷ are identicalor different and are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl,alkylaryl or Si(R²⁸)₃ where R²⁸ are identical or different and are eachC₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl withcyclopentadienyl derivatives of alkali metals or alkaline earth metals,heating the reaction mixture obtained in this way to from −78 to 250°C., with or without addition of free radicals or free radical formers,and, if desired, subsequently replacing the bridged phenolic ligand orthe two unbridged phenolic ligands to form the monosubstitution ordisubstitution product.
 2. A process as claimed in claim 1, wherein R¹and R⁸ in formula I are bulky substituents.
 3. A process as claimed inclaim 1 or 2, wherein m in formula I is
 0. 4. A process as claimed inany of claims 1 to 3, wherein Y¹ are identical and are each oxygen.
 5. Aprocess as claimed in any of claims 1 to 4, wherein cyclopentadienylderivatives of magnesium or lithium are used.
 6. A racemic metallocenecomplex of the formula III

where the substituents and indices have the following meanings: M istitanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium,molybdenum, tungsten or an element of transition group III of thePeriodic Table or a lanthanide, X¹ is

where: R¹, R⁸ are identical or different and are each fluorine,chlorine, bromine, iodine, C₁-C₂₀-alkyl, 3- to 8-membered cycloalkylwhich may in turn bear a C₁-C₁₀-alkyl group as substituent, C₆-C₁₅-aryl,alkylaryl having from 1 to 10 carbon atoms in the alkyl part and from 6to 20 carbon atoms in the aryl part, arylalkyl having from 1 to 10carbon atoms in the alkyl part and from 6 to 20 carbon atoms in the arylpart, Si(R⁹)₃ where R⁹ are identical or different and are eachC₁-C₂₀-alkyl, C₃-C₁₀-cycloalkyl, C₆-C₁₅-aryl, where the radicalsmentioned may be partially or fully substituted by heteroatoms, —OR²⁷,—SR²⁷, —N(R²⁷)₂, —P(R²⁷)₂, where R²⁷ are identical or different and areeach C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl or Si(R²⁸)₃where R²⁸ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl, R² to R⁷ are identical ordifferent and are each hydrogen, C₁-C₂₀-alkyl, 3-to 8-memberedcycloalkyl which may in turn bear a C₁-C₁₀-alkyl radical as substituent,C₆-C₁₅-aryl, alkylaryl having from 1 to 10 carbon atoms in the alkylpart and from 6 to 20 carbon atoms in the aryl part, arylalkyl havingfrom 1 to 10 carbon atoms in the alkyl part and from 6 to 20 carbonatoms in the aryl part, Si(R⁹)₃ where R⁹ are identical or different andare each C₁-C₂₀-alkyl, C₃-C₁₀-cycloalkyl, C₆-C₁₅-aryl, adjacent radicalsR² to R⁷ and may form saturated, partially saturated or unsaturatedcyclic groups having from 4 to 15 carbon atoms, and the radicalsmentioned may be fully or partially substituted by heteroatoms, —OR²⁷,—SR²⁷, —N(R²⁷)₂, —P(R²⁷)₂, where R²⁷ are identical or different and areeach C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl or Si(R²⁸)₃where R²⁸ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl, Y, Y¹ are identical ordifferent and are each

 ═BR¹², AlR¹², —Ge—, —Sn—, —O—, —S—, ═SO, ═SO₂, ═NR¹², ═CO, ═PR¹² or═P(O)R¹², where R¹² are identical or different and are each hydrogen,halogen, C₁-C₁₀-alkyl, C₁-C₁₀-fluoroalkyl, C₆-C₁₀-fluoroaryl,C₆-C₁₀-aryl, C₁-C₁₀-alkoxy, C₂-C₁₀-alkenyl, C₇-C₄₀-arylalkyl,C₈-C₄₀-arylalkenyl, C₇-C₄₀-alkylaryl, or two radicals R¹² together withthe atoms connecting them form a ring, M¹ is silicon, germanium or tinand m is 0, 1, 2, 3, or Y is nonbridging and represents two radicals R′and R″, where R′ and R″ are identical or different and are eachhydrogen, fluorine, chlorine, bromine, iodine, C₁-C₂₀-alkyl, 3- to8-membered cycloalkyl which may in turn bear a C₁-C₁₀-alkyl group assubstituent, C₆-C₁₅-aryl, alkylaryl having from 1 to 10 carbon atoms inthe alkyl part and from 6 to 20 carbon atoms in the aryl part, arylalkylhaving from 1 to 10 carbon atoms in the alkyl part and from 6 to 20carbon atoms in the aryl part, Si(R⁹)₃ where R⁹ are identical ordifferent and are each C₁-C₂₀-alkyl, C₃-C₁₀-cycloalkyl, C₆-C₁₅-aryl ortogether with adjacent radicals R⁴ or R⁵ form saturated, partiallysaturated or unsaturated cyclic groups having from 4 to 15 carbon atoms,and the radicals mentioned may be fully or partially substituted byheteroatoms, —OR²⁷, —SR²⁷, —N(R²⁷)₂, —P(R²⁷)₂, where R²⁷ are identicalor different and are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl,alkylaryl or Si(R²⁸)₃ where R²⁸ are identical or different and are eachC₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl, R¹³ to R¹⁷ areidentical or different and are each hydrogen, C₁-C₂₀-alkyl, 5- to7-membered cycloalkyl which may in turn bear a C₁-C₁₀-alkyl group assubstituent, C₆-C₁₅-aryl or arylalkyl, where adjacent radicals maytogether form cyclic groups having from 4 to 15 carbon atoms, orSi(R¹⁸)₃ where R¹⁸ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl or C₃-C₁₀-cycloalkyl, Z is

 where the radicals R¹⁹ to R²³ are identical or different and are eachhydrogen, C₁-C₂₀-alkyl, 5- to 7-membered cycloalkyl which may in turnbear a C₁-C₁₀-alkyl group as substituent, C₆-C₁₅-aryl or arylalkyl,where adjacent radicals may together form cyclic groups having from 4 to15 carbon atoms, or Si(R²⁴)₃ where R²⁴ are identical or different andare each C₁-C₁₀-alkyl, C₆-C₁₅-aryl or C₃-C₁₀-cycloalkyl, or R¹⁶ and Ztogether form a —[T(R²⁵)(R²⁶)]_(q)—E— group in which T may be identicalor different and are each silicon, germanium, tin or carbon, R²⁵, R²⁶are each hydrogen, C₁-C₁₀-alkyl, C₃-C₁₀-cycloalkyl or C₆-C₁₅-aryl q is1, 2, 3 or 4, E is

where R²⁷ is C₁-C₁₀-alkyl, C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl, alkylaryl orSi(R²⁸)₃ where R²⁸ are identical or different and are each C₁-C₁₀-alkyl,C₆-C₁₅-aryl, C₃-C₁₀-cycloalkyl or alkylaryl.
 7. A racemic metallocenecomplex as claimed in claim 6, wherein R¹⁷ and R²³ are not hydrogen whenR¹⁶ and Z together form a —[T(R²⁵)(R²⁰)]_(q)—E— group.
 8. The use of aracemic metallocene complex as claimed in claim 6 or 7 as catalyst or asconstituent of a catalyst for the polymerization of olefinicallyunsaturated compounds or as a reagent or catalyst in stereoselectivesynthesis.